This invention is directed to high amperage bolted pressure contact switches and more particularly to a combination switch terminal fastener means and instrument tap for such a switch.
In many installations of high amperage bolted pressure contact switches it is necessary or desirable to provide some means for measuring the voltage drop across the switch contacts or across the cartridge fuses that are incorporated in the switch or both. To make these measurements, electrical instrument connections are usually necessary at three locations on the switch structure. Because space is usually limited around these switches, and because foreign objects must be maintained beyond arcing distance and away from the moving parts of the switch, the connections for the instruments are generally made to the switch terminal flanges.
The hard copper which forms the switch terminal flanges is difficult to work; attempts to drill and tap separate holes for each instrument connection generally lead to a high breakage rate for the drills and taps used. Also, since the available space on the switch terminal flanges is often limited, the combination of an instrument terminal and the fastening means for mounting the switch to the insulator board is advantageous. Thus, the instrument terminal of the invention may be associated with the fastening means which are normally provided to hold the switch components to the insulator board.
Other objects and purposes of this invention may be found in the following specification, claims and drawings.